This invention relates to 1-carba(1-dethia)-3-cephem-4-carboxylic acids and derivatives thereof. In particular, it relates to 7-acylamino-(or 7-amino)-3-trifluoromethylsulfonyloxy-1-carba(1-dethia)-3-cephem-4-carboxy lic acids and esters thereof and to a process for preparing 3-chloro and 3-bromo-1-carba (1-dethia)-3-cephem-4-carboxylic acids with the 3-trifluoromethylsulfonyloxy derivatives.
The 1-carba(1-dethia)-3-cephem-4-carboxylic acids, hereinafter 1-carbacephalosporins, possess the 4,6-bicyclo ring system represented by the following formula ##STR1## wherein the numbering of the cepham nomenclature system is used for convenience.
The preparation of 1-carbacephalosporins and C-3 substituted methyl derivatives thereof is taught broadly by Christensen et al., U.S. Pat. No. 4,226,866. Hirata et al., U.K. patent application No. 2041923 teach a process for preparing 3-H and 3-halo 1-carbacephalosporins, while Hatanaka et al., Tetrahedron Letters, 24, [No. 44], pp. 4837-4838 (1983), teach a process for preparing a 3-hydroxy-(.+-.)-1-carbacephalosporin. Because of the importance of these newer .beta.-lactam antibiotics, there is a need for better methods for their preparation and for 1-carbacephalosporins with enhanced potency against infectious and resistant microorganisms.